I'm planning to host my guest executable in Service Fabric cluster but have this doubt that what will happen if my guest executable on Service Fabric node dies?
Will Service Fabric automatically restarts my executable again
Yes it will be restarted when it crashes. Service Fabric detects when a process crashes. It will restart the process that crashed. It will be restarted on a different (healthy) cluster node.
It doesn't matter if you're running a Stateful / Stateless service or a guest executable in this situation. The behavior is the same.